Treatment of some medical conditions involves administering a drug (or a combination of drugs) subcutaneously or intravenously into a patient.
A drug delivery system can be divided in two parts, namely a device for supplying the drug (such as a bag, pump or syringe) and a tubing arrangement for delivering the drug into the patient.
The tubing arrangement includes a soft cannula or catheter. One end of the catheter is inserted into the patient, leaving the other end available for connection to the drug-supplying device. The catheter is held in place by taping the cannula to the surface of the skin of the patient or by using a housing which itself is attached to the surface of the skin.
To insert the catheter into the patient, a device is used which employs an introducer needle, for example as described in U.S. Pat. No. 5,522,803 A. The catheter is carried on the needle such that, when the needle pierces the skin and underlying tissue, the catheter is also inserted. The needle is then withdrawn, leaving the catheter in place.
Most existing insertion devices suffer the drawback that the needle is often exposed before and/or after insertion, thereby allowing possible contamination of the needle and exposing the operator to so-called “needle stick” injury, which carries with it a risk of infection.
One solution is to use protective elements to shield the needle.
For example, US 2004/0158207 A1 describes a device for inserting a cannula which is connected to a base body. The device includes a frame which is used to accommodate the cannula and an operating element which is used to move the cannula out of the protective element.
Although the device can reduce the chance of needle stick injury, the device can be detached from the base body with the needle is still exposed.
WO 2009/007742 A1 describes a cannula insertion device comprising an insertion device in which the needle is shielded before and after it is inserted. The insertion device can only be detached after the needle has been drawn back into the body of the insertion device.